Tail-gate mechanism for trucks



July 13, 1954 L. s. wooo 2,683,540

TAIL GATE MECHANISM FOR TRUCKS Filed Jan. 17, 1952 7 Sheets-Sheet l Fig.l. /0

INVENTOR Louis S. Wood BY CLCJMM mia-aw ATTORNEY July 13, 1954 L.. s.woon 2,683,540

TAIL GATE MECHANISM FOR TRUCKS Filed Jan. 17, 1952 '7 Sheets-Sheet 2INVENTQR Louis S. Wood BY GAAT m d o-Qvn/ ATTORNEY July 13, 1954 L s,WOOD 2,683,540

TAIL GATE MECHANISM FOR TRUCKS Filed Jan. 17, 1952 '7 Sheets-Sheet 5'IVA'. viv l s l P B FIQ. l T T 4 Ju /qil w 2o f`, o

mi /5 L INVENTOR Louis S. Wood ATTORNEY July 13, 1954 L. s. wooo TAILGATE MECHANISM FOR TRUCKS' '7 Sheets-Sheet 4 Filed Jan. 17. 1952lNvENToR Louis S. Wood m ATTORNEY July 13, 1954 sjwoon TAIL GATEMECHANISM FOR TRUCKS '7 Sheets-Sheet 5 Filed Jan. 17, 1952 INVENTORLouis S. Wood ATTORNEY..

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July 13, 1954 Filed Jan. 17. 1952 L. S. WOOD TAIL GATE MECHANISM FORTRUCKS 7 Sheets-Sheet 6 INVENTR .Louis S. Wood ATTORNEY July 13, 1954 L.s. wooo TAIL GATE MECHANISM FOR TRUCKS '7 Sheets-Sheet 7 Filed Jan. 17,1952 lNvENToR Louis S. Wod

ATTORNEY Patented July 13, 1954 UNITED srAr TENT OFFICE TAIL-GATEMECHANISM FOR TRUCKS Michigan Application January 17, 1952, Serial No.266,809

l Claims. l

This invention relates to power-actuated loading and unloading apparatusfor trucks, of the type known as power-actuated tailgate mechanisms. Insuch mechanism a tailgate member is swingable up and down about ahorizontal axis so as to close or open the rear end of the box body of atruck, with the gate member constituting the vertical rear end Wall ofthe body when closed, while when open it forms a horizontal rearwardplatform-like extension of the box bottom. Power-actuated mechanism isprovided whereby the platform can be lowered parallel to itself toground level to present a low ramp for convenient and expeditiousloading, and then be elevated back to box bottom level to allow theelevated load to be conveniently pushed onto the bottom proper, suchpower-actuated mechanism herein being termed the platform elevatingmechanism, or briefly the elevating mechanism. With such mechanismsmanual labor in the loading or unloading operation is required only formoving the load horizontally on and oif the platform, while verticalmovement of the loaded platform as in raising and lowering is effectedby the powered elevating mechanism.

This invention is an improvement over known truck loading apparatus inwhich hydraulic power cylinder means for actuatingr the elevatingmechanism is supplied with pressure iiuid medium such as pressure oilfrom a pump which A is driven by the truck engine and is disposedunderneath the truck body together with other components of thehydraulic system such as pipes, connections, and oil reservoir, theengagement and disengagement of the pump drive as Well as the control ofthe power cylinder and thus of the elevating mechanism having heretoforebeen effected by control valve devices operable from the cab of thetruck. This invention is an improvement over such known power-actuatedtailgate loading and unloading apparatus or platform-elevating apparatusin which the accessories are spread between the front and the rear endof the truck, and which apparatus is thus more or less integrated withor involved in the general construction of the truck and thus dependentupon certain structural environment within the truck as a whole, thatis, dependent upon the arrangement and driving facilities offered by theengine, and dependentupon the chassis frame, as well as dependent uponthe truck body and upon the cab, all in relation to one another.

Such platform loading apparatus as heretofore employed was thereforerelatively expensive and complicated to embody and install in a truckrequiring special provisions and design considerations, While itsunder-the-chassis accessories were spread out between the front and therear of the truck and relatively inaccessible yet relatively exposed todamage from underneath and difficult to inspect and to service. Undersuch conditions only relativelylarge and heavy trucks have heretoforebeen thus equipped while lighter trucks of standard make have had to dowithout the convenience and expediency oifered by such laborsavingpowered loading equipment.

It is among the objects of this invention to provide loading equipmentof the power-actuated tailgate type mountable upon trucks of standardmake which lack the environment for installing or embodying suchequipment in the heretofore accepted manner above indicated; to providepower-actuated platform-loading equipment so constructed that it can beapplied to existing trucks rapidly with a minimum expenditure of labor,without requirement of any special skills, and substantially withoutalteration of any part of a standard make truck not originallyconstructed for the embodiment therein of such equipment; and to providesuch platform-loading equipment that is altogether readily accessiblefor servicing and inspection, that is extremely compact when assembledrather than spread out, that may be shipped compactly preassembledinclusive of accessories and when installed is substantially confinedwith all accessories and control means to the rear end of the truck, andthat can be conveniently operated from the rear of the truck where theloading takes place rather than from the cab.

To attain these objects in a broad sense, this invention providestailgate loading apparatus including electrically powered hydraulicactuating means whereby the actuation, that is, the lowering and raisingof the platform, is rendered independent of any mechanical drivingconnections with the engine as well as independent vof ycontrol from thecab, and which makes it possi-- ble to conne the apparatus with all itsacces'- sories to the rear end of the truck.

More particularly, to attain these objects, this invention provides aself-contained power-actuated tailgate unit attachable to the open rearend of the box body, the unit comprising all operation components andaccessories, to wit, a tailgate or platform, an elevating mechanism orparallel motion device-for the platform, a hydraulic operating systemfor the elevating mechanism complete with pump, power cylinder means,pressure oil lines, oil reservoir, and a manually operable control valveu nit, and furthermore signicantly an electric motor for driving thepump and adapted to be supplied with electric energy as from the truckbattery or other suitable source of electric energy. The self-containedpower-actuated unit according to this invention also includes adaptorstructure whereby it is attached to and mounted upon the open andunencumbered rear end of the truck body with no need to rely upon thechassis or engine environment or the cab of the truck.

According to one feature the attaehable self-- containedplatform-loading unit comprises a first upright U-shaped adaptor frameto be fastened as by means of adaptor or bracket pia-tes to the openrear end of the box body, and a second upright also U-shaped framecarrying swingable thereon the tailgate member or platform, which secondframe is cooperatively associated with and movably interconnected withthe adaptor frame by power-actuated elevating mechanism for lowering andraising the platform through the operation of hydraulic power cylindermeans and a hydraulic control system therefor. Notably, there is mountedupon the adaptor frame and carried thereby a self -contained hydraulicpower unit herein also termed hydraulic power package for actuating theelevating mechanism, which power package contains an oil reservoir, amotor and motor-driven pump for delivering pressure fluid to the powercylinder means characteristically also mounted upon the adaptor frame. Amanually operable spare pump for the hydrauiie system is associated withthe power package, so that the motor-driven pump or the spare pump canbe selectively operatively connected with the oil reservoir of the powerpackage.

In one embodiment the elevating mechanism is in the nature of aparallel-link mechanism co prising a pair of parallel links for eachside, each pair consisting of an upper and a lower link, each pair oflinks having a hydraulic power cylinder unit operatively engaging itwith both cylinders actuated in unison by the power package governed bythe control valve unit. That is to say, each lower link has an armextending from its inner end to which is pivotally connected the outerend of the plunger of a respective power cylinder, the cylinder itselfextending substantially upwardly along a respective side of the adaptorframe and has its upper end pivotally mounted thereon. Pressure oil pipeconduits ex tend between the hydraulic power package and the hydrauliccylinders in closely hugging relationship with respect to the adaptorframe and largely protected and concealed thereby.

In summary, this invention provides poweractuated tailgate loadingapparatus having electrica-lly powered hydraulic actuating means, whichapparatus is attachable to the open rear end of the box body of a truckby means of an adaptor frame fastened to the walls of the body, wherebythe apparatus and all accessories, including manually operated pump, andcontrol means are confined to the rear end oi the truck.

The invention may be embodied in other specic forms without departingfrom the spirit or essential characteristic thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

In the drawings:

Figures 1 to 4 are semi-diagrammatic operational side views of thetailgate mechanism embodiment that comprises a power package, Figure 1showing the loading platform after it has been lowered to the ground,Figure 2 showing the loading platform half raised, Figure 3 showing theloading platform fully raised to a level with the bottom of the truckbody, and Figure 4 show ing the platform swung upward y to body-closingposition.

Figure 5 is an end View of Figure l.

Figure 6 is a top view of Figure 5.

Figure 7 is a perspective view of the tailgate mechanism of Figure 1with hydraulic power package, although detached as a unit from the truckbody, showing bracket plate for attachment of the unit to the body.

Figure `8 shows a View of the mechanism similar to Figure l,self-contained although eduippec with only a hand pump for actuating thepower cylinders.

Figure 9 shows a view of the mechanism similar to Figure l,self-contained and equipped with hydraulic power package as well as withnandactuated pump for optional use of either 'the one or the other.

Figure 10 is a diagrammatic and functional View of the tailgatemechanism and ci' the hydraulic operating system therefor, representedby the hydraulic power package as wei hand-operated pump correspondingto Figure 10 is an end View on line i5 -if'it of the power package.

Figure 11 is a diagrammatic and .functions view of the tailgatemechanism oi the hydraulic operating system therefor, the hydraulicsystem being represented by a hand-eperated pump corresponding tc Figure5.

Figure lln is a sectional side vien1 on line i if* Ila of the hand pumpof Figure 1i.

Figure 12 is a diagrammatic and functional View of the tailgatemechanism and of the draulic operating system therefor, the hydraulicsystem being represented by a hydraulic power package corresponding toFigures i to 7.

The loading apparatus shown in Figures i to comprises parts which arelargely identiabie also in the perspective iew of the apparatus unitshown in Figure 7, like parts designated as far as possible by likenumerals.

The attachable loading apparatus collectively designated by the letter Acomprises as a basic element a vertica adapter frame i5 in the form of avertical U-shape fastened to the open rear end of the box body of atruck T the chassis ci which is indicated at C. The bott in of the boxbody is indicated at B.

The adaptor frame it) is fastened to the bottom of the truck bottom asby means oi bottom bracket plate H and by means of a pair of sidebracket plates l2 and I3. rl`he plate H ex ends iiXedly from the bottomportion H1n of the adaptor frame and rests upon and is supported by andfastened to the bottom B of the body, While the plates i2 and i3 extendfixcdiy from the upright portions or sides Ib and ISC of the adaptorframe and are fastened to correspond ing sides S1 and Sz of the truckbody, such fastening being indicated as by rivets I4 or the like. Thelegs lSb and Ic of the U-shaped adapter frame are of a box-likestructure, each, as best seen in Fig. i, having a wall Id facing theinterior of the truck body and oppositely facing walls Ide withconnecting walls If. The oppositely facing walls Ille are shorter inlength than the inner facing walls Id.

Mounted upon and carried by the adaptor frame It is a platform-carryingelevating mechanism complete and self-contained,l that is inclusive of ahydraulic power package P further described below, for lowering andraising a loading platform F. The mechanism comprises a second verticalU-shaped frame I unitary with the platform F and movably connected tothe adaptor frame I El by means of two pairs of parallel links, namely,one pair of links I6 and I1 at one side and another pair of links I8 andI9 at the opposite side. Thus there is a pair of upper links i6 and I8,and a pair of lower links I1 and IS, both of the lower links beingswingable about a transverse axle 20 mounted in and carried by thetransverse body portion of the U- shaped adaptor frame I0. Each of thelower links thus has a stationary pivot end at axle 20, and each ofthese lower links has extending from the stationary pivot end a shortrigid arm 2l to which is pivotally connected the lower or outer endportion of the plunger 22 of a hydraulic power cylinder P1, one suchpower cylinder being provided at and along each side of the adaptorframe Iii with the upper end of the cylinder having a pivotal mounting23 upon a respective upright side portion of adaptor frame I0. The powercylinders PI are housed within the boxlike formation of the uprightmembers of the U- shaped adapter frame and are partially protected bythe walls of the box. The power cylinders, however, extend beyond atleast one of the walls of the box structure so that the power cylinderand its piston 22 may be accessible for repair thereof. Thus by theoperation of the parallel links mechanism as actuated by the two powercylinders P1 the frame I5 can be bodily lowered and raised parallel toitself as between the level of the bottom B and ground level G, therespective lowered and raised positions of the frame, and thus of theloading platform F being shown in Figures l and 3 respectively. That isto say, when the plungers of the power cylinders are held extended theloading platform will be flush with bottom B; retracting the plungerswill lower the platform through intermediate position (Figure 2) toground position (Figure l).

The hydraulic power package P shown in Figures 1 to '7 as well as inFigure 9 comprises a motor M, a pump U, and an oil reservoir R. Acontrol button switch for starting and stopping the motor M of the powerpackage is indicated at 2d mounted by means of bracket 25 upon theadaptor frame I il. There are various pipes and valves operativelyconnecting the power package with the power cylinders (not shown) inFigures l to '7 but diagrammatically shown and described below in Figurel2 along with a more detailed description of power package P.

"in distinction from the Figures lto 7 embodiment, the Figure 8embodiment omits the hydraulic power package and shows instead the useof a hand-operated pump H which is more fully described along with theoperating system in the diagrammatic Figure ll, whereas Figure 9presents an embodiment showing the provision of an hydraulic powerpackage P as well as of a hand-operated pump H to be used optionallyinstead of the power package P, details of such alternative operationbeing shown in diagrammatic Figure l0 described below.

Description and operation of the operating systems in Figures 10, 11, 12

In the combination of hand pump H and power package P in Figure 10 theoperation of the power package will first be described, whileconnections between the hand pump and the power cylinders may beconsidered inactive.

Pump U of the power package is shown to be in the nature of a rotarygear pump driven by the motor M. The pump has an inlet 25'CL whereby itdraws oil from reservoir R, and an outlet 26 for delivering pressure oilsimultaneously to both power cylinders P1 as by way of oil pipe 21 and apair of branch pipes 28 and 29. An oil return pipe 30 connects pipe 2'Iwith an inlet passage 3I in the pump unit U through which passage oilfrom the power cylinders may be released into the reservoir by way of acontrol valve 32 provided in return pipe 30.

That is to say, with the motor and pump running, if the control valve 32is closed oil being drawn by the pump from the reservoir will bedelivered under pressure through lines 2l, 28, 29 into the powercylinders P1 so as to extend the plungers. 22 thereof downwardly therebyacting upon lever arms 2| in a manner to raise the U- shaped frame I5with platform F until the platform reaches the level of the box body,when continued oil pressure delivered by the pump will be released as byway of a ball relief valve 33 shown in the Figure 10a view of the pump.The pump has a ball check valve 34 at its delivery end which holds theoil pressure in the power cylinders unless relieved by opening of thecontrol valve 32 whereby the platform F will be lowered as oil from thecylinders is being displaced and returned to the reservoir throughpassage 3i due to the Weight of frame I5 and platform F acting toretract the plungers 22 of the power cylinders. In other words, when theplatform F is to be raised from its ground level position to body levelposition, valve 32 is closed and motor and pump are started by pushbutton switch 24 to supply pressure oil to the power cylinders by way ofball check 34. When the fully raised position is reached, the continuedsupply of pressure oil will be diverted through relief valve 33 into thereservoir until motor and pump are stopped, while pressure remains inthe cylinders to uphold the platform in its raised position as the valve32 remains closed. If the platform is to be lowered, it is onlynecessary to open the valve 32 to allow the pressure oil from thecylinders to escape through return line 30 into the reservoir.

In the Figure 10 system, the hand pump H may be used instead of thepower-driven rotary gear pump U, for instance in case the supply oielectrical energy for the pump motor should fail. With the control valve32 closed the hand pump will draw oil by way of a pipe or suction line35 and the passage 3| from reservoir R, while delivering pressure oil asthrough a pipe or pressure line 36. That is to say, pipe 35 joins pipe3U as at point 3'I at one side of valve $2, while -the pipe 35 joinspipe 39 at the other side of valve 32. Thus if pump H is manuallyactuated as by reciprocating a hand lever 3B with valve 32 closed, suchmanual actuation will raise the platform F from its ground levelposition to body level position and hold it there while continued supplyof pressure is relieved through suitable relief valve into theVreservior until actuation of the pump is stopped. The hand pump, ofcourse, has a suitable check valve for one-way passagetherethrough ofpressure oil to the cylinders. If platform F 'is to be lowered, all thatis necessary is to open control valve 32 so that oil from the cylindersmay escape through branches 28 and 29, through part of pipe 21 andthrough return pipe 36 and passage 3l into the reservoir. The hand pumpH is semi-diagrammatically indicated in Figure 10 as comprising a pumphousing 39, a pair of cylinders 4t and 4i with plungers 42 and 43respectively reciprocable in complementary fashion by a tiltable beam 44pivotally mounted at l5 upon housing 39 and connected to the plungers bymeans of links i6 and 'i respectively. As the lever 33 is rocked oroscillated by hand the plungers will alternatingly force pressure oilthrough a common passage i8 in the housing and through a pair of ballcheck valves not shown but indicated by port openings 59 and 50, and outat 5| into the pressure line 35 to the cylinders, while oil is beingdrawn from reservoir R through passage 3|, suction line S5, port 52 andthrough a pair of ball check valves 53 and 54.

In the Figure 11 embodiment of the operating system the power cylindersP1 are shown to be supplied with pressure oil solely from a hand pumpunit H'. By oscillating the hand lever L of this pump unit oil is drawnfrom a reservoir R unitary with the pump, while with a control valve 55in this unit kept closed pressure oil is delivered by this pump througha line 56 and branches 23 and 29 to the power cylinders P1, to effectraising of platform F from ground level to body level. In order toeffect lowering the platform from body level to ground level it is onlynecessary to open the valve 55 which is in the nature of a needle valve,so that pressure oil from the cylinders may be released for escapethrough line 56 into the reservoir as in sinking the weight of theplatform structure in eifect expels the oil from the cylinders.

The hand pump H appears similar to the hand pump H of Figure 10,although differing somewhat with respect to the arrangement of ports andcheck valves therein as well as with respect to the arrangement of thereservoir R. That is, the pump H comprises a housing l having a pair ofcylinders 53 and 59 in which operate plungers S9 and Gi respectively.The plungers are conected to respective ends of beam 32 as by means ofshort links 63 and 66, the beam being rockable by oscillating the handlever L. If the control valve 55 is closed so as to close a port orpassage 65, then the plungers @t and Gi will draw oil from the reservoirR through a passage S6 and by way of a pair of ball checks t? and B8 ina passage 68a, and will deliver it by way of another pair of ball checks69 and 'lll provided in a passage 'il through line 56 and branches 28and 29 to the power cylinders P1, to effect raising of the platform Ffrom ground level position to body level position. In order to lower theplatform it is only necessary to open the control valve 55 so that oilfrom the cylinders or from the pressure side of the pump may escape intoreservoir R', namely by short circuiting from passage 'il past the valve55 to passage S5 leading into the reservoir. In a practical embodimentof this invention this reservoir R is disposed inside the associatedhollow upright portion lilb of the U-shaped adaptor frame l0.

The Figure 12 embodiment of the operating system differs from that ofFigure in so far as it is shown to rely solely upon the functioning ofthe power package P without'making provision for a hand-operatedsparepump to be associated with the power package. However, the operation ofthe power package in Figure 12 is taken by itself the same as theoperation of the power package P in Figure 10, so that its descriptionin the Figure 12 embodiment need not now be repeated.

What I claim is:

1. The combination of a truck having a box body with power-actuatedloading apparatus of the tail-gate type with the tail-gate serving as aloading platform, and for the bottom of the body7 a platform-carryingvertical frame comprising a nrst upright U-shaped frame substantiallycorresponding to the cross-sectional shape of the box body and fastenedto the rear end thereof, each leg of the U-shaped frame being of abox-like formation having a wall facing the interior of the truck body,an oppositely facing wall and connecting walls, some of the walls beingshorter in length than the other walls, a second upright U-shaped framecarrying the platform and in parallelism with the rst frame withparallel motion means operatively interconnecting said frames, anelevating mechanism comprising hydraulic cylinder means mounted withinand supported by the respective legs of the rst frame and partiallyprotected by the walls but extending beyond at least one of the wallsand connected to and actuating the parallel motion means, a power drivenpump connected to the hydraulic cylinders, a fluid reservoir associatedwith the pump, manually actuated control means for controlling theoperation of the cylinders, means for controlling the power drive, anelectric motor for driving the pump, and the pump, reservoir and motorbeing mounted upon and supported by one of the legs of the first frame.

2. The combination of a truck having a box body with power-actuatedloading apparatus of the tail-gate type with the tail-gate serving as aloading platform, and for the bottom of the body, a platform-carryingvertical frame comprising a rst upright U-shaped frame substantiallycorresponding to the cross-sectional shape of the box body and fastenedto the rear end thereof, each leg of the U-shaped frame being of aboxlike formation having a wall facing the interior of the truck body,an oppositely facing wall and connecting walls, some of the walls beingshorter in length than the other walls, a second upright U-shaped framecarrying the platform and in parallelism with the iirst frame withparallel motion means operatively interconnecting said frames, anelevating mechanism comprising hydraulic cylinder means mounted withinand supported by the respective legs of the rst frame and partiallyprotected by the walls but extending beyond at least one of the wallsand connected to and actuating the parallel motion means, a power drivenpump connected to the hydraulic cylinders, a fluid reservoir associatedwith the pump, manually actuated control means for controlling theoperation of the cylinders, means for controlling'the power drive, anelectric motor for driving the pump, and the pump, reservoir and motorconstituting a single unit and being mounted upon and supported by oneof the legs of the first frame.

3. A tailgate type loading mechanism adapted for attachment to a boxbody of a truck in which the tailgate constitutes a loading platform,comprising a vertical U -shaped adaptor frame adapted to be fastened tothe open end of the box`body, each leg of the U-shaped frame being of aboxlike formation having a wall facing the interior of the truck body,an oppositely facing wall and connecting walls, some of the walls beingshorter in length than the other walls, a second U- shaped verticalframe carrying the platform, parallel link elevating mechanismoperatively interconnecting said frames, a pair of hydraulic powercylinders one housed in each leg of the adaptor frame partiallyprotected by the walls but extending beyond at least one of the wallsfor actuating the elevating mechanism; a hydraulic pump, a motortherefor, and a reservoir for operating the power cylinders and mountedupon and carried by one leg of the rst U-shaped frame.

4. The mechanism according to claim 3, with the addition of hand pumpmeans operatively ascociated with said power cylinders and also mountedupon and carried by one leg of the first U-shaped frame.

5. The mechanism according to claim 3, in which the pump, the motor, andthe reservoir constitute a package unit.

6. The mechanism according to claim 3, with the addition oi hand pumpmeans operatively associated with said power cylinders, said hand pumpmeans, said pump, said motor and said reservoir constituting a packageunit.

7. A tailgate type loading apparatus adapted for attachment to a boxbody of a truck in which the tailgate constitutes a loading platform,comprising a vertical U-shaped adaptor frame adapted to be fastened tothe open end of the box body, each leg of the U-shaped frame being of abau-like formation having a wall facing the interior of the truck body,an oppositely facing wall and connecting walls, some of the walls beingshorter in length than the other walls, a second 1-shaped Vertical framecarrying the platform, parallel link elevating mechanism operativelyinterconnecting said frames, a pair of hydraulic power cylinders onecarried within each leg of the adaptor frame partially protected by thewalls but extending beyond at least one of the walls for actuating theeleva-ting mechanism, hydraulic pump means and a reservoir for operatingthe power cylinders and mounted upon and carried by one leg of the firstframe.

8. Apparatus according to claim 7, in which the pump means comprise ahand-operated pump.

9. A. tailgate type loading apparatus adapted for attachment to a boxbody of a truck in which the tailgate constitutes a loading platform,comprising a vertical U-shaped adaptor frame having bracket platesextending from the bottom portion and from the sides of the adaptorframe for attachment to the bottom and the sides of the body, each legof the U-shaped frame being of a box-like formation having a wall facingthe interior of the truck body, an oppositely facing wall and connectingwalls, some of the walls being shorter in length than the other Walls, asecond U-shaped vertical frame carrying the platform, parallel linkelevating mechanism operatively interconnecting said frames, a pair ofhydraulic power cylinders one housed in each leg of the adaptor framepartially protected by the walls but extending beyond at least one ofthe walls for actuating the elevating mechanism, and actuating means forthe power cylinders, the actuating means being mounted upon and carriedby one leg of the first frame.

10. A tailgate type loading mechanism adapted for attachment to a boxbody of a truck in which the tailgate constitutes a loading platform,comprising a vertical U-shaped adaptor frame adapted to be fastened tothe open end of the box body, each leg of the U-shaped frame being of abox-like formation having a wall facing the interior of the truck body,an oppositely facing wall and connecting walls, some of the walls beingshorter in length than the other walls, a second U-shaped vertical framecarrying the platform, parallel link elevating mechanism operativelyinterconnecting said frames, a pair of hydraulic power cylinders onecarried within each leg of the adaptor frame partially protected by thewalls but extending beyond at least one of the walls for actuating theelevating mechanism, a power-driven hydraulic pump, a motor therefor, areservoir for operating the power cylinders and mounted upon and carriedby one leg of the first frame, a hand-operated hydraulic pump, and meansfor selectively operatively as sociating said power-driven pump or saidhandoperated pump with said reservoir.

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